1. Field of the Invention
The invention relates to a device for locking a position of a moving part with respect to a fixed part.
2. Description of the Related Art
When there is the desire to lock, precisely, the position of a moving part with respect to a fixed part, it is necessary to have control both over the relative position of one part with respect to the other and over the locking of this position.
Isostatic positioning constitutes precise and repeatable positioning. The locking of such positioning often entails several maneuvers, and this makes the device more complicated and lengthens the time taken to operate it.
By way of example, mention may be made of a moving part positioned with respect to a fixed part on a plane in eliminating three degrees of freedom of the moving part with respect to the fixed part, in a straight line parallel to the plane eliminating two other degrees of freedom, and at a point distinct from the straight line and from the plane and eliminating the last degree of freedom. To lock this position, use is made of a clamp, the force of which opposes the loss of contact of the moving part with respect to the positioning plane. Before tightening the clamp, it is necessary to apply to the moving part one or more other additional forces separate from the force applied by the clamp, to press the moving part against the straight line and the positioning point. Once the clamp has been tightened, it is possible to release the additional force or forces. The moving part is then held with respect to the fixed part against the straight line and the positioning point by adhesion. In the abovementioned example, if the additional force or forces are not sufficient, there is the risk that it will not be possible to obtain correct bearing against the straight line or the point, and that correct positioning will thus be compromised. In addition, it is necessary to carry out at least two maneuvers in order to lock the position. A first maneuver consists in applying the additional force or forces and a second maneuver consists in tightening the clamp. The need for these numerous maneuvers increases the time taken for positioning and for locking.
It is an object of the invention to alleviate these drawbacks by providing a device which is simple and quick to operate.
To achieve this object, the subject of the invention is a device for locking a position of a moving part with respect to a fixed part, the moving part being positioned with respect to the fixed part isostatically, characterized in that the device comprises means generating a force opposing the loss of contact of all the points of isostatic contact between the moving part and the fixed part so as to lock the position.
One advantage associated with the isostatic positioning is that good repeatability can be attained in successive positionings of the moving part with respect to the fixed part, even if the two parts, or at least their areas of contact, are not produced precisely. The absence of the need for precision also makes it possible to reduce the cost of producing the two parts.
The invention finds a particular use in the mounting of an optomechanical component on a helmet. This component comprises, for example, a pair of night vision goggles.
In this example, it is necessary for the pupil of each half of the goggles to be positioned precisely in front of the eye of the person wearing the helmet. The invention allows sufficient precision during successive removals and remountings of the optomechanical component. The invention also allows the person wearing the helmet to mount the optomechanical component blind with just one hand, that is to say without being able to see the positioning means and the locking means.